There are several ways to monitor and control the level of a liquid in a reservoir, particularly a swimming pool. The most primitive way to monitor and control the level of a liquid is by visual inspection and manually filling. Because manually controlling the level of a liquid in a reservoir, such as a pool, is not usually a feasible alternative, various systems have been developed for automatically controlling liquid levels, particularly the water level in a pool.
U.S. Pat. No 4,445,238 to Maxhimer discloses an apparatus for remotely sensing the water level in a pool and turning on and off a flow of water via a control valve. In Maxhimer, water is drawn from a skimmer reservoir of a pool into a cylinder, the level in the cylinder thus reflecting the height of water in the pool. As the water level in the cylinder changes, a float in the cylinder either allows an photo detector to detect light from an LED, activating water flow, or disrupts the light detection by the photo detector.
U.S. Pat. No. 5,203,038 to Gibbs discloses an apparatus for maintaining a water level in a swimming pool. The level sensing device includes a floatation element operable to float on the surface of the water and having a floatation arm connected to the valve assembly to open and close the water conduit. The floatation element has a sensing device attached to the end portion of the main body for sensing variations in the level of fluid. Accordingly, the need exists for a water level maintenance apparatus which is operable with swimming pools having a wide range of configurations.